This invention relates to an improved slidable carriage mount for a linearly reciprocable data transducer in a disc memory storage apparatus.
FIGS. 1 through 4 show a conventional carriage device for a disc memory storage apparatus as described in Japanese patent application No. 55-116673, wherein an optical read/write data transducer 10 for a memory disk (not shown) is mounted to a carriage 1 slidable on a pair of parallel guide rods or rails 2a and 2b disposed at opposite sides A and B of the carriage. Two identical pairs of symmetrically arranged and longitudinally spaced bearing rollers or wheels 3a, 4a and 3b, 4b are mounted on side A of the carriage and ride on the guide rail 2a. A single pair of similar bearing rollers 3c and 4c is mounted on a metal spring plate 5 secured to the other side B of the carriage, and ride on the guide rail 2b. The guide rails are fixed on a base 6. A linear motor coil 11 (shown only in FIG. 1) is fixed to the carriage 1, and cooperates with magnetic core structures 12a and 12b disposed on opposite sides thereof.
When a target position on a disk has been determined, electric current is fed to the coil 11 in response to instructions from a control unit, and the carriage is driven in the X direction to access the target position.
Due to the inclinations of the respective upper and lower bearing rollers 3a, 3b, 3c and 4a, 4b, 4c and the force exerted by the spring plate 5, all of the rollers are urged against their associated guide rails 2a, 2b to slidably and stably support the carriage.
Any rotational movement of the carriage around the Y and Z axes is restrained by this construction when the driving force acts at the approximate center of gravity of the carriage, and a stable linear reciprocal movement of the carriage along the guide rails is thus attained.
In such a conventional construction, however, the large mass of the carriage tends to twist the metal spring plate 5 when the carriage is quickly moved in the X direction, and the resulting rotational movements of the carriage around the X axis produce harmful vibrations in the carriage which adversely affects its positioning accuracy. The protrusion of the spring plate from the side of the carriage also increases the size of the overall construction.